With the advent of highspeed interconnections, computer resource management has become ubiquitous for networked systems. For instance, systems are needed to support increasing storage requirements to meet growing application and enterprise needs. Systems that previously relied on stand-alone or dedicated external storage devices, have migrated towards expanded resources available through networked storage. Further, networks and associated interface technologies have evolved from simple hub and spoke applications to complex and robust switched networks with multiple sub-nets, zones, segments, WANs and the Internet.
The complexity and volume of such networks has prompted some system designers to physically or logically consolidate storage resources, as well as adapters and/or servers. Such structure may promote substantial performance gains. An example of one such an architecture includes Storage Area Networks (SANs). SANs are centrally managed, highspeed storage networks consisting of multiple storage systems, storage management software, application software, application servers and network hardware. SANs expedite information access, storage and protection to campus, industry and metro environments. SANs may be based upon storage protocols and interconnects that enable “any-to-any” connectivity between servers and storage. Adapters of SAN networks support interconnects to multiple operating systems and environments.
One principal feature of an adapter, or a comparable computer interface, is enabling communications between a processor or server complex with one or more peripheral resources. Namely, adapters account for diverse characteristics, applications and hardware designs of such resources to simplify interconnections. For instance, an adapter may manipulate or translate the content or protocol of signals emitted from a server in such a manner that a peripheral device may readily process them. As such, adapters and associated software-executing mechanisms can provide a highly configurable and flexible interface for peripheral resources. As a result, device-specific operations can be “wrapped” to provide a common software interface that effectively permits data exchange without any special regard for the specific intricacies of the underlying hardware. As such, adapters typically incorporate a physical connector required to connect the peripheral resource to a host or server system.
In this manner, the proper operation of adapters is critical to the access of networked servers, as well as to overall system operations. Despite their relative importance to SAN operations, adapters remain vulnerable to failure. Causes of adapter failure include hardware and software complications, as well as general aging considerations. An adapter may also go offline in response to losing a connection or pathway through the interface. In many systems, regaining connectivity between a server and storage may require physically removing and replacing a failed adapter.
Replacing an adapter may require that at least a portion of the system be shut down and rebooted. In multi-user computer environments, where system availability is critical, an inability to access a resource for any amount of time may have a significant impact on the productivity of a relatively large number of users and operations. In many mission-critical applications, any such downtime is intolerable.
Consequently, some system designers attempt to introduce redundancy into networks in the form of dedicated, replacement adapters. More specifically, some network architectures may specifically allocate a backup adapter for each primary adapter. As such, a system with four primary access adapters will merit four dedicated, replacement adapters. Ideally, each backup adapter may intervene to enable a host access to a resource in the event of its primary's failure. For example, the responsibilities of the failed adapter may be passed to the designated replacement adapter.
Such conventional replacement procedures, however, burden host servers with substantial processing requirements. Host responsibilities may involve coordinating the replacement of adapters. A host system must conventionally initiate and direct all corrective and reconnecting processes. Each host must know and evaluate all pathways to a resource, and must further monitor and navigate adapters and resources, alike. Such requirements detract from other host processes and retard system performance. Furthermore, some servers do not support programming sufficient to execute such procedures. The duplicate adapters further represent additional equipment costs and often complicate network designs.
Therefore, a significant need exists in the art for a manner of providing robust access to a resource with minimal negative impact on system processes and design.